The present invention relates to home security systems and in particular to a short-range wireless security system having a plurality of distributed sensor transmitters, each being coupled to a transducer, and at least one user data input transmitter. Each transmitter is RF coupled to a system controller and which in turn is coupled to a central station. The invention is further characterized in that each distributed transmitter is serially programmable with a plurality of unique system parameters identifying the transmitters and selectable sensor options and which pre-condition pulse position encoded messages transmitted thereby relative to a transducer type, type of sensed condition and the system and transmitter identification data.
With the advance of micro-electronics, wireless home security systems have become economically more feasible. Such systems, like garage door openers, currently and most commonly utilize an RF communications link between various remote sensors and a system controller. Cumbersome and expensive wiring is thus avoided, but in replacement of which it is now necessary to provide means for addressing each message to allow the system controller to identify and distinguish each sensor and the data transmitted thereby. For example, it is necessary to know not only which sensor is transmitting at any given time, but also the type of sensor so as to further determine whether or not an indicated alarm condition is in fact an alarm.
Sensor identification has heretofore typically been achieved by including within each sensor a plurality of DIP switches, fusible links or other physically programmable bistate devices, not to mention hard wiring particular wires to particular pin locations and whereby a unique address is assigned to each transmitter. Thus with each subsequent transmission, the programmed address is transmitted along with sensor condition data, typically a single bit, to enable the system controller to identify the origin of system transmissions. With the exception of each sensor's address, however, essentially no other transmission pre-conditioning has been used. All other signal conditioning, such as timing delays to accommodate the various types of sensors etc., has been relegated to hard wiring either provided in the sensors or at the system controller. Thus, the task has been left to the system controller to decode the sensor transmissions and determine whether or not, (with a change in a sensor's state), a valid alarm is bein detected.
An example of one such system can be seen in U.S. Pat. No. 4,360,801 and wherein a home security garage door operating system is disclosed which is also responsive to toxic gas and heat buildup. Each sensor transmitter in this system is assigned a five-bit address established by five selector switches mounted at each remote sensor module. Light emitting diodes are also provided to confirm address selection. Each transmission, in turn, is encoded via a pulse width modulated transmission schema. Each sensor's address and the state of its associated transducer is thus transmitted as a single message to a central control module whereat the messages are decoded and an appropriate alarm condition is set. Also provided at the central control module is sensor compensation circuitry and which in the case of the carbon monoxide detector comprises time delayed circuitry allowing for warm-up of the associated reference circuitry. Similarly, motor lockout circuitry is provided to prevent against door closure after the detection of carbon monoxide buildup.
Yet another security system and which is dependent upon Manchester phase encoded RF transmissions is disclosed in U.S. Pat. No. 4,257,038. Here again individual short-range RF sensor transmitters are utilized to communicate alarm conditions to a central station and which is responsive to a transmitted change in sensor condition from a pre-set initial condition at the central station. The system is constructed from a family of integrated programmable encoder/decoder circuits, in particular a Model ED-11 encoder/decoder manufactured by Supertex, Inc. These circuits are configurable as either transmitters or receivers and operate on parallel input data that in the case of a transmitter is converted to a serial Manchester encoded output, although without error detection. When configured as a receiver, the circuitry receives, converts and compares the received data to previously programmed data. Alarm conditions are determined by applying a sensor output to a programming input terminal, where it is subsequently transmitted upon enabling the transmitter. Each remote sensor when activated, transmits a uniquely encoded transmission, different from each other transmitter, that is subsequently decoded by the central station to identify the transmitting sensor and indicate a change in state and an alarm condition. All decoding is left to the central station and therefore no pre-conditioning occurs at any of the transmitters.
Still another patent of which applicant is aware is U.S. Pat. No. 4,231,105 and wherein a vending machine control unit is disclosed that is operable in response to data entered via a programming unit. In particular, unit prices may be selectively changed via a connector coupled hand-held programming unit that operates in a byte parallel fashion to re-program an electrically erasable read only memory stored in the control unit. In contrast thereto, the present invention utilizes a battery powered, serially programmable recirculating shift register schema for programming pre-conditioning parameters into the system sensors and user data input transmitters. The present schema also allows the immediate reading of entered data to confirm proper entry.
While systems like those described in the foregoing patents achieve a similar end to the present system, that is, of identifying alarm conditions, the present system is constructed to do so in a fashion which provides for maximum flexibility and ease of system programming. In particular, it achieves this end by permitting the programming of the system sensor transmitters and each user data input transmitter such that the messages transmitted therefrom directly identify to the system controller not only which transmitter is transmitting, but also pre-condition the transmission to account for any peculiarities of its associated transducer. Message processing is thus limited at the system controller. A single sensor transmitter can also be adapted to accommodate a broad range of systems and transducer types in a cost effective fashion. Similarly, multiple user data input transmitters can be used in a single system to facilitate operation.
Accordingly, it is an object of the present invention to enable the programming of the sensor and user data input transmitters via a hand-held system programmer and whereby sensor address, type and a number of sensor or system dependent parameters can be programmed without having to physically disassemble the sensors and/or data input units.
It is another object of the invention to minimize the pin count of each programmable integrated circuit transmitter via serially programmed re-circulating shift registers provided thereat.
It is another object of the invention that each transmitter transmit pulse position encoded messages to the system controller and wherein two bits of data are identified by a single pulse within each data frame pulse and wherein each message is transmitted a multiplicity of times depending upon the message type, thereby assuring reception at the system controller.
It is a still further object of the invention to permit not only the programming of the sensor and user data input transmitters, but also the interrogation of previously programmed system parameters therein.
It is a still further object to allow the programming of each sensor and user data input transmitter with a specific house code.
It is a still further object to provide a plurality of programmable pre-conditioning options at each sensor transmitter identifying ones of the following conditions: supervised, sensor type, sensor switch condition, sensor switch restore, lockout timing, emergency priority, smoke delay and transmitter frequency select; along with sensor identification data identifying the sensor number.
The above objects, advantages and distinctions of the present invention will become more apparent upon reference to the following description thereof with respect to the appended drawings. Before referring thereto, however, it is to be appreciated that the following description is given by way of the presently preferred embodiment only and accordingly various modifications may be made thereto without departing from the spirit and scope of the following described invention. Such description should also not in any way be interpreted to limit the scope of the invention. It is to be further appreciated that to the extent like numerals are used in the various drawings, they described like components.